Hermetic compressor

ABSTRACT

A MULTI-CYLINDER HERMETIC COMPRESSOR WITH MEANS FOR VARYING ITS CAPACITY BY POSITIVELY CLOSING OFF THE FLOW OF SUCTION GAS FROM THE LOW SIDE OF THE SYSTEM TO ONE OR MORE CYLINDERS. THE SUCTION GAS IS NORMALLY DELIVERED TO A CHAMBER WHICH SUPPLIES AT LEAST ONE CYLINDER AT ALL TIMES. THE GAS THEN FLOWS THROUGH A PASSAGE TO ANOTHER CHAMBER SUPPLYING A SECOND CYLINDER OR GROUP OF CYLINDERS. A FLUID OPERATED CAPACITY CONTROL VALVE IS ARRANGED IN THIS PASSAGE TO POSITIVELY SHUT OFF FLOW TO THE SECOND CHAMBER TO PREVENT GAS FROM BEING SUPPLIED TO CYLINDERS RECEIVING GAS FROM THE SECOND CHAMBER. THE CAPACITY CONTROL VALVE IS OPERATED BY HIGH PRESSURE DISCHARGE GAS, THE FLOW OF WHICH IS CONTROLLED BY AN INTERNALLY MOUNTED SOLENOID VALVE LOCATED IN A LINE BETWEEN THE CAPACITY CONROL VALVE AND A SOURCE OF DISCHARGED GAS WITHIN THE COMPRESSOR.

June 20, 1972 F. M. LAucKs ETAL 3,671,147

HERMETIC COMPRESSOR Filed Deo. 30, 1969 3 Sheets-Sheet 1 ATTO RN EY June20, 1972 F, M, LAUCKS EI'AL 3,671,147

HERMETIC COMPRESSOR Filed Dec. 30. 1969 5 Sheets-Sheet 2 woo i l WW;

tr-'WZ 12 A51 sa sie 30 64 ATTOQN EY June. 20, 1972 F. M. LAucKs Er AL3,671,147

HERMETIC COMPRESSOR Filed Dec. 30, 1969 3 Sheets-Sheet 3 1| NVENTOQS 131D 152 130 MMA/4a 4m/5 104 wafers www ATTORNEY United States Patent OU.S. Cl. 417-286 3 Claims ABSTRACT F THE DISCLOSURE A multi-cylinderhermetic compressor with means for varying its capacity by positivelyclosing off the ilow of suction gas from the low side of the system toone or more cylinders. The suction gas is normally delivered to achamber which supplies at least one cylinder at all times. The gas thenliows through a passage to another chamber supplying a second cylinderor group of cylinders. A lluid operated capacity control valve isarranged in this passage to positivelyshut off llow to the secondchamber to prevent gas from being supplied to cylinders receiving gasfrom the second chamber. The capacity control valve isoperated by highpressure discharge gas, the flow of which is controlled by an internallymounted solenoid valve located in a line between the capacity controlvalve and a source of discharge gas within the compressor.

CROSS REFERENCE TO RELATED APPLICATION BACKGROUND AND SUMMARY OF THEINVENTION This invention relates generally to reciprocating hermeticcompressors and, more particularly, to means for varying the capacity ofa multi-cylinder compressor.

A number of capacity control techniques and means for unloading one ormore cylinders within a compressor have been described in the prior art.One well known technique is that of holding open the suction valve sothat the suction gas is not subjected to the work capable of being doneon it by the piston. The suction gas enters the cylinder during thesuction stroke and is forced back into the suction plenum during thedischarge stroke. Another technique, which is similar to the oneutilized in the present invention, s referred to as suction gasthrottling. In this system, some means are provided for controlling theow of suction gas from the evaporator to the compressor. If the flow ismodulated, it often causes overheating of the compressor due to thethermodynamic losses inherent in suction gas throttling. The presentinvention utilizes a system which completely cuts ofI" the gas flow fromthe low side of the system to the gas working space. In such case,heating of the cylinder is restricted to that which is generated by thefriction of the piston working in the cylinder.

Mechanisms for controlling the flow in the manner just described havebeen suggested in the prior art. For example, in U.S. Pat. 3,061,176issued to A. 1J. Nicholas et al. on Oct. 30, 1962, there is described acompressor in which the cylinder is provided with an annular sleevecompletely surrounding the same. The sleeve is adapted to be moved, bymeans of a hydraulic actuator, to a position which closes off theflow ofgas from the suction Patented June 20, 1972 "ice manifold to the suctionvalve. One problem which is inherent in a compressor of this type isthat it is diicult to obtain the proper sealing of the suction gas flowcontrol sleeve. The sleeve has a diameter somewhat greater than thecylinder and any cocking or misalignment of the sleeve may cause gasleakage.

In the present invention, the suction gas ilow control valve is positivesealing and is completely incorporated within the housing containing thecylinders and the crank shaft. By providing a casting with integralpartitions appropriately located within the space surrounding thecylinders, independent suction gas chambers can be used to supplyparticular cylinders. Flow passages can then be conveniently formedbetween the chambers; and a valve positioned within these passages canthus be constructed in a very simple manner. This permits the use ofsmall diameter valves and valve seats which assure adequate gas sealing.Moreover, the number of parts required to accomplish positive suctiongas cut-off is greatly minif mized. In fact, the llow control valve foreach section of the compressor merely comprises a simple sleeve valveand a spring to bias the valve in an open position.

Accordingly, it is a principal object of the invention to provide acapacity control system particularly suited for a multi-cylinderhermetic compressor in which the liow passages and the ow control valveare contained in the cylinder housing section of the compressor.

Another object of the invention is to provide a compressor havingpartitions between certain cylinders so that independent control of asingle cylinder is possible.

Another object of the invention is to provide a capacity control inaccordance with the above stated object which can be constructed at lowcost and which will operate in a trouble free manner, thus requiringlittle or no maintenance.

Still another object of the invention is to provide a capacity controlsystem in which the gas throttling losses are minimized, therebyassuring a cooler operating compressor.

Additional objects and advantages will be apparent from reading thefollowing detailed description taken in conjunction with the drawings. v

DETAILED DESCRIPTION OF THE DRAWINGS FIG. 4 is a cross-section viewta'ken alon ln 4 4 of FIG. 3. g l e DETAILED DESCRIPTION OF THISlINVENTION Referring rst to FIG. 1, there is shown a compressor which iscompletely enclosed within a hermetically sealed shell 10, normallyfabricated by using a lower half 12 and a dome 14. Suction gas inletconnection 16 at the upper end of the dome delivers suction gas to theinterior of the compressor shell.

The compressor comprises a lower body or housing section 18 containingthe cylinders 20, 21, 22 and 23; an

electric motor 24, mounted on the upper section body 26; a crank shaft28 driven by the motor; and connecting rods 30 driving pistons 32. Whilethe compressor illustrated utilizes four cylinders, it is obvious thatany configuration utilizing two or more cylinders may be constructed`without departing from the principles of the invention.

The suction gas, after entering through the inlet connection 16, passesdownwardly through the motor stator 34 and rotor 36 to effect coolingthereof, the gas being constrained to ow through the motor by means of ashroud 38 which rests on the upper body section 26. The gas passingthrough the motor ows through a pair of ports, 40, 41 in the upper body(only one of which is shown in FIG. l) and then down into a pair ofchambers surrounding certain of the cylinders.

As best shown in FIGS. 2 and 3, the cylinder jackets are integrally castwith the lower housing section 18 in a staggered array; and eachincludes a pair of passages 46 extending longitudinally of the axis ofthe cylinder permitting the gas to flow into a suction gas plenum 48formed between the distal portion of the cylinder jacket, provided witha flange 50, and the head 52. The valve plate assembly 54 is constructedof a series of laminated plates which form a plurality of suction gaspassages '56 leading to suction valve 58 and a discharge valve 60communieating with a series of circumferentially spaced discharged ports62.

During the discharge stroke, with suction valve 58 closed, the gas iscompressed by the piston 32 until the gas has suflicient pressure toopen the discharge valve 60 and release it into the head. Each of theheads `52 is interconnected with a tubular conduit 64 leading to amuffler assembly 66 surrounding the motor housing and which is connectedto a discharge line 68 leading outside of shell \10. The entirecompressor unit is suspended inside the shell by means of a series ofspring mounts 70 including a lower support 72 attached to the inside ofthe shell and springs 74 receiving mounting tubes 76 on the upper bodysection 26.

Attention is now directed to FIG. 3 which shows in more detail the lowerbody section containing the cylinders. It will be noted that the castingfrom which the lower body is formed includes a plurality of verticalwalls 80, `81, 82 and 83 which function as partitions to separate allfour cylinders. These partition walls thus form separate chambers 84,85, 86 and 87 associated with cylinders 20, 21, 22 and 23 respectively.Between certain pairs of chambers, for example, between chambers 8S and86, there is a thickened wall section or boss 90 which is provided witha bore 92 receiving a flow control valve 94. The suction gas is alwaysfed through the two ports 40 and 41 (which would open into the areabounded by dotted lines in FIG. 3) in the upper body into the chambers85 and 87 which supply suction gas to cylinders 21 and 23 respectively.However, in order to pass from. chamber 85 to chamber 86, the gas mustHow through a port 96 (FIG. 4) into the bore 92' and downwardly throughanother port 98 which opens into chamber 86.

The other valve I95, arranged in partition wall 80, controls the flow ofgas from chamber 87 to chamber 84 in the same fashion. The valveelements 94 and 95, which are moveable within bores 92, are each biasedto an open position by a resilient member such as spring 100. Thechambers 102 and 103 above valve elements 94, 95 communicate with asource of high pressure fluid, such as the discharge gas, by means of aconduit 104 leading from the muifler 66 to a solenoid valve 106 which isselectively energized through electrical conductors 108 extendingoutside the shell.

Lines 110 and 111 connect solenoid valve 106 with chambers 102 and [103respectively through passages 112 and 113 which intercept relieved areas114, 115 providing flow passages between the upper and lower housingsections above valve elements 9'4, 95.

The solenoid valve 106 may be of any conventional type having a valvebody 116 having ports 117, 118 and 119 and a moveable spool 130 havingpassages 131 and 132. In the spool position shown in FIG. 3, passage 131interconnects ports 118 and 119. Port 118 is connected to a pair offluid lines 120 and 121 leading respectively to suction gas chambers 86and 84 via ports 122 and 123. Port 119 is connected to flow controlvalves 94 and 95 through tluid lines i110 and 111. Thus, passage 131allows the pressure in valve operating chambers 102 and 103 to equalizewith the pressure in suction gas chambers 86 and 84 permitting spring100 to return the valves to their open position.

When valve spool 130 is shifted to the left (as viewed in FIG. 3),passage 132 conducts gas at discharge pressure from line 104- to port119* and then through lines 110 and 111 to close the valves. While onesolenoid valve may be used to operate both of the ow control valveswithin the compressor, it is obvious that individual solenoid valvescould be provided. In this way, selective control of each of the pairsof cylinders can be achieved.

OPERATION Full capacity- When operating under full capacity, the sucitongas flows down into the motor and through the two ports 40, 41 in theupper body and into chambers 85 and 87. When the ow control valve 94 isbiased to its open position by spring 100, the suction gas flows inchamber 85 through the port 96 in the valve housing boss past valve 94and into chamber 86 through a port 98 on the opposite side of the valvehousing boss. If the ow control valve 95 in wall is also open, gas owfrom chamber 8-7 to chamber 84 will be in the same manner. In this way,al1 cylinders are supplied with gas which then flows through passages 46into the suction plenums 48' and then through the suction valves 58 andinto the cylinders. During the discharge stroke of pistons 32, the gasis forced into each of the heads 52 and up through tubes 64 into themuffler 66, and then out through the discharge line 68.

Partial capacity When the operator requires reduced capacity, heactuates the solenoid valve 106 which causes high pressure gas from themuler to be directed to the chambers 102, 103 above the valves 94, 95 byway of line 104, port 117, passage 132, port 119 and lines 110 and 111.The pressure acting on the top of the valves overcomes the spring forceand closes the valves against the seats at the lower end of bores 92,93. This closes olf the tlow of gas from chamber to chamber 86 (and fromchamber 87 to chamber 84), thus completely stopping the flow of gas tocylinders 20 and 22. The compressor then continues to operate with onlycylinders 21 and 23 functioning.

When it is required to return to full capacity, the solenoid valve isdeactivated, returning the spool to the position shown in FIG. 3'. Thisallows the high pressure gas in chambers 94 and 95 to bleed back throughlines 120, 121, port 118, passage 131, port 119' and lines 110, 111 andequalize the pressure with that of suction ygas charnbers 86, 84. Withthe pressure equalized, the spring 100 returns valves 94, to the openfull capacity position.

While this invention has been described in connection with a certainspecific embodiment thereof, it is to be understood that this is by wayof illustration and not by way of limitation; and the scope of theappended claims should be construed as broadly as the prior art willpermit.

What is claimed is:

1. A hermetic compressor comprising a housing having at least a firstand second cylinder provided therein; a hermetically sealed shellsurrounding said housing; a piston received in each cylinder adapted toreciprocate therein; a cylinder head positioned at the end of each saidcylinder; a suction valve and a discharge valve associated with each ofsaid cylinder heads for respectively admitting a uid to be compressed insaid cylinder and for discharging the compressed fluid from saidcylinder; means delining independent rst and second chambers surroundingsaid rst and second cylinders and communicating respectively with thesuction valves of said rst and second cylinders, said chamber definingmeans including a common partition wall separating said rst and secondchambers; means defining a fluid passage in said common partition wallproviding uid communication between said irst and second chambers; valvemeans cooperating with said fluid passage to control fluid ow betweensaid iirst and second chambers; and means for delivering suction gasinto said first chamber; whereby suction gas to said second cylinder maybe controlled by said valve means.

2. A compressor as defined in claim 1, including operator means foractuating said valve means, said operator means including anelectrically actuated valve adapted to selectively direct high pressuregas from compressor discharge to said valve means for actuating thesame.

3. A compressor as defined in claim 1, wherein said housing isconstructed of two complementary housing sections including a iirstsection containing said cylinders and a second section receiving suctiongas; a motor adapted to drive said pistons supported in said secondhousing section; and means for causing said suction gas to ow throughsaid motor in heat exchange relation.

References Cited UNITED STATES PATENTS 1,081,176 12/1913 Wainwright417-2286 1,117,394 11/1914 Joleen 4l7-295 2,350,537 6/1944 Scott 417-2953,448,918 6/1969 Cawley 417-371 CORNELIUS I. HUSAR, Primary Examiner I.I. VRABLIK, Assistant Examiner U.S. C1. X.R. 417--295, 371

